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Iron-catalysed lipid peroxidation in rice seedlings under osmotic stress

Jiang Mingyi, Guo Shaochuan

Departhment of Biology,Xiangtan Teacher^s College.Xiangtan 411201,Hunan

Abstract

Seedlings of hybrid rice (Oryza sativa L.) were exposed to osmotic stress by PEG 6000 (-0.7 MPa) and the contents of ferrous iron(Fe~(2+)),hydrogen peroxide (H_(2)O_(2)) and malondialdehyde (MDA) and the rate of production of superoxide radical (O~(.)_(2)) were measured. Under osmotic stress, the increases of contents of Fe~(2+) and H_(2)O_(2) and H_(2)O_(2) and rate of O~(.))_(2) production were accompanied by an increase of content of MDA. A very correlation (P<0.01) was observed between Fe~(2+) content and MDA content. Pretreatment with Fe~(2+),Fe~(3+),H_(2)O_(2),Fe~(2+)+H_(2)O_(2) and the inhibitor of SOD, sodium diethyldithiocarbamate (DDTC), obviously promoted lipid peroxidation, but the iron chelator, di ethylenetriaminepentaacetic acid (DTPA), retarded the increase of MDA. Application of the hydroxyl radical scavengers, mannitol and sodium benzoate, markedly inhibited the lipid peroxidation of Fe~(2+) mediated under osmotic stress. These results indicate that iron-stimulated lipid peroxidation in rice seedlings is mainly due to the formation of highly reactive hydroxyl radical (·OH) by superoxide driven Fenton reaction catalysed by iron under osmotic stress, but a complex between oxygen and different valence states of iron has little effect on lipid peroxidation.

Key words: Osmotic stress;Iron ion;Hydroxyl radical;Lipid peroxidation;Rice seedlings

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Citing This Article：

Jiang Mingyi, Guo Shaochuan. Iron-catalysed lipid peroxidation in rice seedlings under osmotic stress. Acta Physiol Sin 1996; 48 (1): (in Chinese with English abstract).